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A090236 Puzzle-Box primes (bases). 1


%S 11,13,17,31,47,53,71,79,97,113,127,131,137,139,191,199,227,229,233,

%T 313,317,331,347,349,353,359,367,419,449,457,467,479,491,503,557,569,

%U 571,577,607,617,619,647,677,691,751,757,761,797,829,839,859,911,919,929,937

%N Puzzle-Box primes (bases).

%C Puzzle-box primes are intended to pique the interest of young school children in playing with numbers. The name is inspired by another Livermore resident, Harry L. Nelson, co-discover of M27 in 1979 and a maker of manipulative puzzles sometimes featured in the local press.

%F These are the base primes for the puzzle-box lids. When a lid is prime, the base is included in this sequences. Two primes form the box when the digits of the lid, placed over the base, line up to form the same number vertically. In the base prime, the largest digit is chosen, plus 1. All digits in the base prime are then subtracted from this number.

%e a(1)=13. 13 is the base. When the prime lid, 31, is placed above the base 13, it forms a box: 31 over 13 and the two columns add to 4 and 4 [since 3 is the largest digit in the base, 3+1=4, all columns in base and lid must add to this number].

%Y Cf. A090233.

%K easy,nonn

%O 0,1

%A _Enoch Haga_, Jan 23 2004

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Last modified June 25 17:46 EDT 2022. Contains 354851 sequences. (Running on oeis4.)